Möglichkeiten der adiabatischen Präzisionskalorimetrie zur Kinetikaufklärung

The investigation of the hazardous potential of reaction courses is very important for the chemical industry. Compared with the isoperibolic the adiabatic calorimetry has essential advantages for kinetic evaluations, because corrections of heat flux are not necessary. With the adiabatic precision calorimeter ACTRON 5 is the investigation of reaction courses in small volumes possible. The possibilities of the nonlinear investigation program TA-kin are shown with examples of Semi-Batch-Measurements. With this program the change in heat capacities whilst encoring the second component is included.

Professor Hans-Joachim Seifert zum 65. Geburtstage gewidmet     

2-甲基-2-丁醇的低温热容和热力学性质

本文用精密自动绝热量热仪测定了2-甲基-2-丁醇在80～305 K温区的热容,从热容曲线(Cp-T) 发现三个固－固相变和一个固－液相变, 其相变温度分别为T = 146.355, 149.929, 214.395, 262.706 K。从实验热容数据用最小二乘法得到以下四个温区的热容拟合方程。在80～140K温区, Cp,m = 39.208 + 8.0724X - 1.9583X2 + 10.06X3 + 1.799X4 - 7.2778X5 + 1.4919X6, 折合温度X = (T –110) / 30; 在 155 ～ 210 K温区, Cp,m = 70.701 + 10.631X + 12.767X2 + 0.3583X3 - 22.272X4 - 0.417X5 + 12.055X6, X = (T –182.5) /27.5; 在220 ～ 250 K温区, Cp,m = 99.176 + 7.7199X - 26.138X2 + 28.949X3 + 0.7599X4 - 25.823X5 + 21.131X6, X = (T – 235)/15; 在 270～305 K温区, Cp,m =121.73 + 16.53 X- 1.0732X2 - 34.937X3 - 19.865X4 + 24.324X5 + 18.544X6, X = (T –287.5)/17.5。从实验热容计算出相变焓分别为0.9392, 1.541, 0.6646, 2.239 kJ×mol-1; 相变熵分别为6.417, 10.28, 3.100, 8.527 J×K-1×mol-1。根据热力学函数关系式计算出80～305 K温区每隔5 K的热力学函数值 [HT –H298.15]和 [ST –S298.15]。     

CuCl/沸石双功能羰基化催化剂催化合成叔碳酸

Bifunctional carbonylation catalysts were prepared by introducing both of acidic and metallic sites into zeolites, such as β, M and Y, by which tertiary butyl acid was synthesized under mild reaction conditions. The effects of reaction temperature and the copper amount as well as the acid strength on the catalytic activity were investigated. The results show that when the content of cuprous for β, M and Y are 2 35%, 2 48% and 7 13% respectively, the carbonylation activity of the related sample is the greatest. In the reaction temperature range, lower temperature is favorable for yielding acid and higher temperature is favorable for yielding ester. The catalytic activity increases with the increase of the acid strength. The in situ FT IR study shows that Cu(Ⅰ) is the metallic active site.     

Decomposition of Sodium Trichloroacetate in the Presence of Quaternary Ammonium under Microwave Irradiation: A Convenient One‐Pot Synthesis of α‐Hydroxy Acids in Water

A good yielding phase‐transfer‐catalyzed procedure for one‐pot preparation of α‐hydroxy acids from carbonyl compounds and sodium trichloroacetate by in situ addition and hydrolysis under microwave irradiation is described. Decomposition of sodium trichloroacetate is strongly accelerated by the presence of quaternary ammonium. The reaction can be conducted in water.     

Ultrasound‐Assisted Synthesis of β‐Enaminonitriles in the Presence of Base

Application of ultrasound shows significant rate enhancement for the synthesis of β‐enaminonitriles in the presence of base. The role of various homogeneous and heterogeneous bases/solvents was also studied for the reaction, and potassium t‐butoxide/t‐butyl alcohol combination was found to give the best result at room temperature.     

Determination of cymoxanil in drinking water and soil using high-performance liquid chromatography

We describe a method for determination of cymoxanil, 1-2-cyano-2-methoxy(iminoacetyl)-3-ethylurea, in drinking water and in soil, using reversed-phase HPLC with UV detection at 240 nm and a mobile phase of acetonitrile-water (30:70, v/v). Fortified water samples (1.0 L) were extracted with solid-phase extraction on Strata X. Soil samples (20 g) were extracted with acetone and the extracts were transferred onto Strata C18E. The recoveries of cymoxanil from water and soil samples were over 85% for each fortification level. The RDS were within the range 1.7-4.1% for water and 0.9-1.2% for soil samples. After optimization of the extraction and separation conditions, the method was validated.     

Determination of phenolic compounds in environmental water samples after solid-phase extraction with β-cyclodextrin-bonded silica particles coupled with a novel liquid-phase microextraction followed by gas chromatography-mass spectrometry

A novel approach for the sample pre-treatment and determination of eight phenolic compounds in environmental water samples has been developed by hyphenating solid-phase extraction (SPE) and liquid-phase microextraction (LPME) techniques based on solid organic drop combined with gas chromatography-mass spectrometry detection (GC-MS). After pre-concentration and purification of the sample through column containing 60 mg of β-cyclodextrin-bonded silica particles as stationary phase, under the optimum conditions, LPME technique has been performed on the eluent solution. Under the selected conditions, limit of detection (LOD) of 0.002-0.04 μg/L (S/N=3), limit of quantification (LOQ) of 0.007-0.15 μg/L (S/N=10), pre-concentration factor of 752-3135 and linearity range of 0.01-25 μg/L have been obtained. A reasonable repeatability (RSD≤9.5%, n=5) with satisfactory coefficient of determination has been obtained between 0.9981 and 0.9997. The relative recoveries of the waste, sea, river and well water samples were higher than 79%.     

Development of a Sensitive Method for the Determination of 4‐(Methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol in Human Urine Using Solid‐phase Extraction Combined with Ultrasound‐assisted Dispersive Liquid–liquid Microextraction and LC‐MS/MS Detection

An efficient and sensitive analytical method based on molecularly imprinted solid‐phase extraction (MISPE) and reverse‐phase ultrasound‐assisted dispersive liquid–liquid microextraction (USA‐DLLME) coupled with LC–MS/MS detection was developed and validated for the analysis of urinary 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol (NNAL), a tobacco‐specific nitrosamine metabolite. The extraction performances of NNAL on three different solid‐phase extraction (SPE) sorbents including the hydrophilic‐lipophilic balanced sorbent HLB, the mixed mode cationic MCX sorbent and the molecularly imprinted polymers (MIP) sorbent were evaluated. Experimental results showed that the analyte was well retained with the highest extraction recovery and the optimum purification effect on MIP. Under the optimized conditions of MIP and USA‐DLLME, an enrichment factor of 23 was obtained. Good linearity relationship was obtained in the range of 5‐1200 pg/mL with a correlation coefficient of 0.9953. The limit of detection (LOD) was 0.35 pg/mL. The recoveries at three spiked levels ranged between 88.5% and 93.7%. Intra‐ and inter‐day relative standard deviations varied from 3.6% to 7.4% and from 5.4% to 9.7%, respectively. The developed method combing the advantages of MISPE and DLLME significantly improves the purification and enrichment of the analyte and can be used as an effective approach for the determination of ultra‐trace NNAL in complex biological matrices.     

钠硼硅酸盐玻璃分相微结构的NMR研究

采用 ²⁹Si、 ¹¹B MAS NMR研究了组成点位于Na₂O-B₂O₃-SiO₂三元体系玻璃分相区内的玻璃,探讨组成点不同及处理温度不同产生的分相微结构的差异,以便从微结构角度阐明分相的机制。结果表明：在相同温度下位于反常线上的组成点不混溶程度最大。而当组成点固定、分相温度愈低,［BO₃］向［BO₄］的转化率愈大。研究结果提供了     

硬脂酸钠在蓖麻油/水界面上自组装动力学的研究

以电沉积铜为探针,循环伏安法研究硬脂酸钠在蓖麻油/水界面上自组装的动力学.在涂有蓖麻油的石墨粉-环氧树脂固态电极上,硬脂酸钠自组装膜形成过程可由电沉积铜阳极峰监测,遵从高斯函数生长动力学,生长速率常数为km=0.0006292(±0.0000294)s-1.硬脂酸钠自组装膜能较好地控制铜粒子的球形生长和生长尺度,形成硬脂酸钠自组装-铜纳米粒子复合膜.铜粒子在石墨粉-环氧树脂固态电极上为半球形生长,而在涂油和自组装电极上为球形生长.与蓖麻油涂层相比,石墨粉-环氧树脂固态电极与沉积铜间存在弱相互作用(ΔG0=3.86kJ/mol),而硬脂酸钠羧基与沉积铜也有较弱的相互作用(ΔG0=-2.412kJ/mol).